It is known, from French Patent 2,172,485, to convert the angular displacements of a weather vane into a variation in intensity of an electric current so as to be able to display at a distance, with the aid of an ammeter, the wind direction. Such installations are used in meteorology and in particular in airfield control towers.
It is also known, from French Patent 2,170,964, to arrange in a circle pilot lamps for displaying the position of a speed and direction anemometer and the wind force. To do this, magnetic cams are mounted on the spindle of the weather vane and these control contactors for application of voltage to the pilot lamps; the illumination of the lamps can be modulated according to the wind velocity.
A light column is also known, from the PCT Patent application WO 94 14150, the external wall of which is intended to serve as a display carrier and comprises, at its top, a solar sensor which orientates itself according to the position of the sun.
The document DE-C-901,634 discloses a device in which the compass dial is divided into sectors having each a determined color and corresponding to the wind direction. The speed of the wind is also displaid.
The document EP-A-0,365,047 discloses a device showing the air pollution level.
However, none of these devices makes it possible to give, at a distance and in darkness, a simple and direct indication, which is nevertheless adequate for the most usual requirements, of the wind direction and wind velocity and of the air pollution level, without any aesthetically detrimental effect.